Tag Archives: CommRadio

A Tale of Two Radios: CommRadio CTX-10 vs. Elecraft KX2

The following review first appeared in the February 2020 issue of The Spectrum Monitor magazine.

A Tale of Two Radios: CommRadio CTX-10 v Elecraft KX2

As my blog readers often point out: Why focus on low-power (QRP) ham radio activities when propagation is so dismal…even for high power stations? A logical argument, I’ll admit, and lately it’s become a common theme in QRP discussion.

But I’ve said it before, and I’ll say it again: despite the current stagnation of the sunspot cycle, we’ve been seeing a very curious uptick in low-power radio innovation. Manufacturers have been churning out QRP transceivers at a rapid rate during this solar lull, and I can assure you, it’s a strategic move that the marketplace rewards.

So, why should this be? I attribute the influx of QRP radios to several factors.

First of all, leveraging innovations in SDR (software defined radio) design, it’s simply become less expensive to produce portable low-power radios with extra features. In other words, manufacturers can now offer more radio bang-for-buck. Similarly, the technology is accessible enough that even smaller manufacturers can produce competitive products.

Secondly, the new-found popularity of field activities––such as Parks On The Air (POTA) and Summits On The Air (SOTA)––fuel the need for field-portable, all-in-one transceivers. Anyone who falls in love with field portable operation, and it’s easy to do, will quickly discover how handy it is to have a dedicated radio for these activities.

However, it’s not always competition that pulls radio operators to the field. With so much QRM (human-generated interference) at home or in built-up areas, many operators and radio enthusiasts now take to the field to escape the noise. Likewise, many operators live in restricted communities that don’t allow for permanent antennas, so it’s in their best interest to make their radio shack…well, portable.

And why not? Weak-signal digital modes like FT-8 have made signal-hopping across the planet with only a few watts of power easier than ever before. I’ve spoken with a number of operators who have––using FT-8––worked DXCC for the first time with stealthy, portable antenna systems, and others who have taken the dare to work DXCC only on individual bands. Such challenges are all in the name of fun.

Finally, in general, QRP transceivers are much less expensive than their 100 watt counterparts. QRP radios gain a competitive edge by omitting pricey amplification in the design, while still offering the operator DX-class features and receiver performance.

Making a choice

With so many new field-portable QRP transceivers on the market, making a choice can be difficult. Still, there are some guidelines that will help you eliminate a number of models.

The Mountain Topper MTR5B

For example, if you only plan to operate CW and don’t need a general coverage transceiver, you can effectively eliminate all of the priciest QRP transceivers. CW-only transceivers like the popular Mountain Topper series are incredibly portable, durable, and half the price of full-featured multi-mode transceivers.

Also, if you use resonant antennas, there may be no need for an internal or external antenna tuner––this can save you upwards of $200. If you prefer using an external battery, there may be no need to purchase a model with an internal battery option.

In this article, however, we’ll be looking specifically at two general coverage QRP transceivers that are very much all-in-one. With an antenna, mic and/or key, these radios will get you on the air in a matter of seconds.

Our competitors

Over the past year, I’ve received numerous emails and comments asking for advice choosing between two specific radios: the recently reviewed CommRadio CTX-10 and the Elecraft KX2.

I’m not surprised, because both of these field-portable QRP transceivers sport similar basic features and options, e.g.:

Ham band coverage from 80 – 10 meters
General coverage receiver
Internal batteries
Built-in ATU
Small and lightweight
Designed and built in the USA

Although the CTX-10 and KX2 share the same goal of functioning as an all-in-one, grab-and-go field radio, I believe they have very different appeal.

Herein lies the key to choosing the right rig for you, and the point I hope to prove in this article: it’s based on your personal operation philosophy.

The Elecraft KX2 is the “Swiss army knife” transceiver. It has an amazing array of capabilities, features, and adjustments, yet is incredibly compact and could easily fit in your jacket pocket. Moreover, the KX2 is backed by Elecraft, one of the most successful amateur radio manufacturers in business.

The CommRadio CTX-10, on the other hand, was designed with a basic feature set in mind, dead-simple operation, and near mil-spec quality inside. The CTX-10 is the transceiver iteration of the popular CR-1 series receiver by CommRadio.

When I’m asked which radio is best, I respond with a series of questions––because I first need to discover what type of operator the potential user is, to give him/her a good recommendation. Below, I’ll break down some of the key questions to help guide you in making a decision between these two transceivers. Note that these questions are ones that should be asked when purchasing pretty much any transceiver.

Do you plan to engage in more ham radio operation, or broadcast listening?

True, since the CTX-10 and KX2 are both general coverage transceivers, either radio can serve. But if you’re primarily looking for a broadcast listening radio and you might only occasionally hop on the bands to make casual ham radio contacts, then you should give the CTX-10 some consideration.

The CTX-10 is essentially a transceiver version of the excellent CR-1a receiver. It is better equipped for listening to broadcasts than the KX2 because it has three AM filter settings: 5, 7.5, and 15 kHz. In contrast, the KX2 AM filter can only be widened to about 5 kHz. CTX-10 AM audio fidelity is superior to that of the Elecraft KX2.

In addition, the CTX-10’s receiver coverage dips down to 150 kHz and it’s quite capable on the mediumwave band. The KX2’s receiver covers 3 MHz – 32 MHz and 0.5 – 3 MHz with “reduced sensitivity.” In other words, the KX2s receiver architecture is designed for the ham bands, thus mediumwave sensitivity is suppressed on purpose. I’ve certainly listened to mediumwave stations on the KX2, but only to local, strong stations. You could never hop into mediumwave DXing on the KX2 like you can on the CTX-10.

With that said, if you’re primarily looking for a ham radio transceiver for operations in the field, and you might only occasionally do shortwave radio listening, then you should give the KX2 serious consideration. In my opinion, the KX2 is simply a more capable, adaptable ham radio transceiver than the CTX-10. (More details on this point to come.)

The Elecraft KX2 doing a little coastal SWLing.

Now, here’s the irony: Although I had a CTX-10 in my shack for almost a year, I still defaulted to taking the KX2 on trips when I thought SWLing might be my primary activity. Why? The KX2 has a very robust and capable HF receiver. Its only real limitations are a lack of wide AM bandwidths and sub-3 MHz frequency coverage and performance. I find that the KX2’s 5 kHz AM filter sounds pretty good, though; when using headphones, the KX2’s simulated stereo audio effect really makes the audio sound broad and pleasant. I also rarely use ham radio transceivers to do mediumwave or longwave DXing––I use dedicated portables like my Panasonic RF-2200, or an SDR––so mediumwave and longwave reception is never a serious limitation for me.

But, again, if you primarily plan to do broadcast listening, the CTX-10 is the stronger of the two choices.

Are you looking for a feature-packed radio that can be tweaked and adjusted on a granular level?

If so, you’ll definitely want to choose the KX2 over the CTX-10. The CTX-10 has an incredibly basic feature set, while the KX2, like most Elecraft radios, has an abundance of features, functions, and adjustments at your disposal.

If you want a simple, unfussy radio that automatically adjusts most user controls like microphone gain and compression, then the CTX-10 will suit you fine. If you like both automatic and manual control of your radio’s settings, the Elecraft KX2 is your rig.

How important is internal battery operation and ease of recharging?

The CTX-10 has best-in-class internal battery capacity and intelligent charging. You can literally play radio for hours on end without depleting the batteries in the CTX-10. The internal batteries can be charged via the DC power port, or even via USB cable.

The KX2 Battery

The KX2 uses an internal battery pack that must be removed each time to charge. I’ve taken the KX2 to the field more than 100 individual times and find that I can operate at full power for about one hour fifteen minutes (with a heavy amount of transmitting) before the voltage drops, and the output power, as well from about 10 watts to 5 watts. Of course, when in receive, it’ll operate for hours without recharging.

Of course, with a swappable battery pack, you can bring additional pre-charged batteries to the field to eliminate the need to recharge.

I’ve never found recharging or swapping KX2 batteries to be a problem, but internal battery operation via the CTX-10 is certainly its strong suit.

One known issue with some of the CTX-10 units: when charging the internal Li-Ion cells, my initial evaluation unit produced a high-pitched audible whine. I measured the audio frequency with a simple smartphone app and determined that it hovers around 10.5 kHz. It was quite annoying because I can still hear frequencies in that range. The second evaluation unit didn’t have this problem. If your CTX-10 has this problem, contact CommRadio for help.

Are you primarily a CW operator?

If you are a CW enthusiast, chances are great that you’ll prefer the KX2 over the CTX-10.

The CTX-10 has very few settings for CW mode. In fact, it doesn’t even (presently) have a side tone control or support iambic operation. The CTX-10 uses a traditional relay for TX/RX switching, but you can’t presently change the hang/delay time. The CTX-10 cannot do full break-in QSK.

Elecraft transceivers are designed by CW operators and sport true benchmark CW performance. The KX2 allows granular control, thus can be tailored to accommodate any operator. The KX2 has silky-smooth full break-in QSK. If you’re a CW operator, you’ll much prefer the KX2.

Are you primarily a digital mode operator?

The CTX-10 body (left) is essentially a large heat sink.

If so, you’ll want to consider the CTX-10, because it can run high-duty cycle modes like FT-8 in the field without ever overheating. This is also one of the CTX-10’s strongest points.

Both the Elecraft KX2 and KX3 will decrease power output after running FT-8, for an extended period of time, to protect the finals from overheating. Operation time can be significantly extended by adding an optional third-party heat sink. The CTX-10 does not have this issue, however, as the CTX-10 body itself is essentially a heat sink. In all of my testing, I never came anywhere close to overheating it.

Are you primarily an SSB/phone operator?

If SSB is your game, you’ll prefer the KX2.

The CTX-10 essentially has no microphone controls––in fact, it doesn’t even have an adjustable mic gain. The microphone input is completely auto-controlled by the CTX-10, via a limiting pre-amplifier, built-in compressor, and ambient noise gate. The only ways you can really affect how audio is transmitted, in fact, is by changing the distance from your mouth to the mic, and/or changing how loudly you speak into the mic.

If you have a favorite boom headset (like Inrad or Heil), note that it may not work well with the CTX-10, simply because you have no control of the mic inputs.

The KX2, on the other hand, has robust microphone controls; you can, for example, even change the EQ settings of your transmitted audio.

How important to you is the capability of your rig’s internal ATU?

The CTX-10 sports a nifty internal antenna tuner, but it doesn’t match the performance of the KX2’s internal ATU option. In my field work, I found that I needed antennas that were pretty close to resonant for the CTX-10 to match them. The ATU was certainly a handy feature on the CTX-10, but it didn’t allow me the flexibility to, for example, load up a random wire antenna.

Update (23 Mar 2020): Brian Haren informs us that with firmware update 1334 issued by CommRadio on December 18, 2019 “performance of the internal tuner was vastly improved.” This firmware was issued after my review unit was sent back to CommRadio.

The KX2’s internal ATU, on the other hand, is benchmark, and can tune via nearly any antenna––indeed, it would almost tune a metal chair, if you tried to load it. It’s as good at matching antennas as my Emtech ZM-2 balanced line tuner. In fact, I once loaded a 20-meter hex beam on 40 meters with the KX2 in order to work a rare park activation. No other radio in my arsenal could match that (well, frankly, it was asking a lot), but the KX2 not only matched the antenna, but it got an excellent match: if memory serves, something like 2:1. (And, yes, I worked my park!)

Note that the ATU comes with the CTX-10 package, while the KX2 internal antenna tuner is a worthwhile $200 option.

Are you on a budget?

Everything included in the CTX-10 box.

When you purchase the CommRadio CTX-10 for $999.99, you’re buying an all-in-one package: a transceiver, internal batteries, and an internal ATU. There are no other options to purchase separately. The CTX-10 doesn’t ship with a microphone, but it does include a USB cable, DC power cord, and CD manual. You simply unbox your CTX-10, make sure it’s been charged, plug in your microphone (requires a modular plug type like the Yaesu MH-31A8J or MFJ-290MY) or key, add your antenna, and boom! You’re ready to hit the air.

Unlike CommRadio, Elecraft started as a kit manufacturer. Their philosophy has always been one of purchasing a basic unit, then adding features when you’re ready. In a sense, this gives the customer a lower starting price point. Here’s how the KX2 pricing breaks down:

Elecraft KX2 transceiver: $789.95
KXAT2-F internal ATU option: $199.95
KXBT2 Internal Lithium Battery option: $59.95
KXBC2 Lithium battery fast charger: $29.95
KXIO2 Real-Time clock: $79.95

To configure the KX2 to be equivalent to the CTX-10––meaning, with ATU, internal battery, and charger––your total price would be $1,079.80. This is the configuration of my KX2.

If you use just an external battery and resonant antennas, the base KX2 might be the only radio you’ll ever need. At $789.95, that’s $210 less than the CommRadio CTX-10. Fully configured, however, the CTX-10 is about $80 less expensive than the KX2.

Apples to oranges, in radio terms

If you haven’t gathered already, although both the CTX-10 and KX2 are general coverage QRP transceivers, they are completely different––like comparing apples to oranges––in terms of the market they wish to reach.

No doubt, CommRadio designed the CTX-10 to appeal to people who love commercial or military channelized radios. Based on my interaction with CTX-10 owners, many are into preparedness and primarily infrequent simplex SSB operations.

The KX2 will appeal to hams who are active operators and who enjoy full control of their radio’s functions and features. Elecraft has a massive and loyal community of users and fans.

Summary

If I haven’t made it clear yet, there’s much more involved in making a purchase decision than simply looking at the specifications of a radio. Often, it’s a truly personal and subjective choice.

Be honest with yourself about your needs, and base your purchasing decision on those. After all, in this case we’re talking about two capable radio transceivers, either of which should provide years of great operation and listening.

Click here to check out the Elecraft KX2 and here for international distributors.

Click here to check out the CommRadio CTX-10 and here to purchase via Universal Radio.

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Final review of the CommRadio CTX-10 QRP general coverage transceiver

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Earlier this year I published what I called an “initial” review of the CommRadio CTX-10 QRP transceiver, promising an eventual final review. The reason for this is that I sensed there were important CTX-10 updates on the horizon, and I wanted to re-evaluate the rig once the upgrades had been implemented through firmware.

This final review builds upon the initial review––think of it as the second installment, or “Part 2″––so if you’re considering the purchase of a CTX-10 and haven’t read the previous post about it, please do read the initial review first.

Upgrades

As anticipated, via simple at-home firmware updates, since my initial review the CTX-10 has now been upgraded and tweaked a number of times. [Click here to view all of the documented firmware updates and notes at CommRadio.]

I’ve been very pleased with the attention CommRadio has paid to their customer feedback on some of the most important requests.

Instead of reiterating what I wrote in the initial review, I’ll jump straight into the upgrades.

Operating split

At time of posting my initial review, the CTX-10 didn’t have A/B VFOs. This was my primary gripe about the CTX-10, because without A/B VFOs, there was no way to operate split, which meant that you could not work DX stations that use split to manage large pileups. This is actually a really important feature for a QRP radio because during split operation, a pileup is pulled apart across a few kHz of bandwidth, thus giving a 10-watt signal a better chance of being heard through a collection of legal-limit signals.

On June 10, 2019, CommRadio released a firmware package that added A/B VFOs and the ability to operate split to the CTX-10.

Even though there are only a limited number of buttons on the front panel, it’s incredibly simple to enter into split mode:

Chose the frequency and mode;
Hold the STEP button for one second or more, then release. You’ll then see a split display indicating the TX and RX frequencies.
Use the left arrow key [<] to toggle between them.

I do like the clear TX and RX lines, which leave no doubt in the user’s mind what the frequency used for transmitting and receiving is. On some radios, this can be a bit confusing.

Split operation is simple and effective, thus I consider this issue fully resolved.

ATU flexibility

In my initial review, I noted that the CTX-10 ATU needed near-resonant antennas for the ATU to make a strong 1:1 match. Indeed, a number of times I actually used a near-resonant antenna in the field––the EFT Trail-Friendly, for example––and the ATU couldn’t get below a 3:1 match. For what it’s worth, CommRadio states that the CTX-10 can easily handle 3:1.

Making a Parks On The Air activation at Tar Hollow in Ohio.

CommRadio has made modifications to the ATU function, improving the performance of the antenna-tuner algorithm, which had a significant impact on 80 and 60 meters. I’ve also had better luck with a number of field antennas I’ve tried on 40 and 20 meters. Is it as good as the Elecraft KX-series ATUs? No.

Having a built-in ATU on the CTX-10 is certainly a valuable feature in the field. When I need to match a challenging antenna with the CTX-10, I bring my Emtech ZM-2 manual tuner along for the ride.

SSB operation?

There still is no way to adjust the microphone gain control nor microphone compression on the CTX-10. Much like a military or commercial radio, the CTX-10 is optimized for just one style of mic: in its case, the modular MFJ-290MY or Yaesu MH-31A8J handheld mic.

The CTX-10 microphone input has a limiting pre-amplifier with built-in compressor and ambient noise gate–in short, the CTX-10 handles all microphone settings automatically.

Through firmware updates, a number of positive adjustments have been made to the microphone settings:

the microphone-decay timer has been tweaked so that audio clipping is less of a concern
audio clarity and gain have been improved
audio power has been improved resulting in .5 to .75 watts of additional peak power
microphone audio leveling has been improved
VOX attack and decay timing has been improved

These are all welcome adjustments.

I would note here, though, that if you plan to use a mic other than the MFJ-290MY or Yaesu MH-31A8J handheld mics, you will have a limited means of adjusting the mic parameters unless you have an external mic EQ. A number of readers, for example, have asked about using their Heil boom headset with the AD-1-YM cable adapter on the CTX-10. Boom headsets are a wonderful tool for field operation because they free your hands to log contacts. As for using boom headsets on the CTX-10, since I don’t have the appropriate adapter, I can’t speak to this. But since you can’t control mic gain, it might take time to learn how to position the boom mic and adjust your voice level for optimum performance.

CW operation

As mentioned in our initial review, the CTX-10 does not support QSK/full break-in operation. Rather, the CTX-10 uses a traditional relay for switching between transmit and receive. During CW operations, you’ll hear a relay click when switching from TX to RX and back again.

The CW hang time delay on the CTX-10 is not currently adjustable. For high-speed CW ops that prefer a faster relay recovery, I suspect this could be an annoyance.

There have been recent CTX-10 firmware upgrades that have helped solve issues found with CW keyer timing in early units. I found the timing issues were mainly present while sending high-speed CW (25 WPM+). My buddy Vlado (N3CZ) put the CTX-10 through some high speed tests, and was pleased with the results overall.

I will reiterate here that the CTX-10 lacks other controls many CW operators appreciate. Currently, the CTX-10 lacks a sidetone control; as a result, you cannot change the sidetone volume/tone, nor can you turn it off. I continue to hope that CommRadio will fix this quirk via a future firmware upgrade.

The CTX-10’s built-in CW keyer does not currently support iambic keying. Meaning, when both levers of a dual paddle are closed simultaneously (squeezed), it will not send a series of alternating dots and dashes. I imagine this could be addressed in a future firmware update.

Additionally, without re-wiring your paddle, you can’t change which side of your paddle sends ‘dits’ and which sends ‘dahs.’ A minor con, for sure–still, most modern QRP transceivers allow you this flexibility.

Revisiting the basic feature set

Let’s be clear: as I stated at length in my initial review, the CommRadio CTX-10 was designed around simple operation, like one might expect from a military or commercial channelized radio. I know ham radio operators and preparedness enthusiasts who prefer this approach to gear design, and they will appreciate this CTX-10 design philosophy.

Still, the CTX-10 lacks many of the features and adjustments you’d typically find on a QRP transceiver in its price class. Instead, the CTX-10 was designed to handle many of these adjustments automatically.

The CTX-10 still has no separate RF gain control. The CTX-10’s RF gain is directly tied to the three AGC settings (slow, medium, and fast). While I believe it does a fine job of adjusting RF gain, I do ride an RF gain control a lot during noisy summer conditions, and miss this feature.

The CTX-10 still has no passband (PBT) control, notch filter, or noise blanker––all features I’d normally expect in a QRP radio at this price level.

There are no CW (os SSB) memory keyers. I wouldn’t expect these, as I believe only the Elecraft KX2 and KX3 sport this feature in this price class of QRP radios.

Also, the ARRL lab reports of the CTX-10 are found in the July 2019 issue of QST (Bob Allison, WB1GCM) noted:

Though adequately sensitive, its third-order IMD and blocking gain compression dynamic ranges, as measured in our laboratory, are more suited to casual operation with antennas of modest gain.

Even with the AGC disabled, one or more strong, adjacent signals will result in the reduction of speaker volume, and I was unable to measure the reciprocal mixing dynamic range (RMDR).

The dynamic range was reported as 58 dB, which is a very low number. Blocking was 65 dB.

Update, 25 Nov 2020: Rob Sherwood recently tested and added the CTX-10 to his receiver test data table.

Out of his comprehensive table which includes vintage radios, the CTX-10 scored the lowest of all of them sorted by third-order dynamic range narrow spaced. It is literally at the bottom of his list: at time of posting, number 146 out of 146 tested radios. Rob concluded that an out-of-passband signal that is approximately S9 will start blocking the radio. Click here for his full notes (PDF).

The CTX-10 doesn’t really have the tool set or receiver performance to cope well with contests or DX conditions.

Please note: as with most firmware-based radios, some missing features could potentially be added in future firmware upgrades. If one of these items is keeping you from purchasing the CTX-10, please contact CommRadio and inquire.

Is the CTX-10 for you?

The CTX-10 on air at the W4DXCC conference

With the most recent upgrades, CommRadio has solved the major issues that kept me from recommending it in my initial review. I still feel there are more capable portable transceivers for the $1,000 US price.

The addition of split operation was especially key for me, as I do operate split. The more nuanced adjustments to the CW keyer, an extra feature to prevent the radio from accidentally turning on while in transit, and the adjustments to the mic algorithm, all make this radio more pleasant to operate at home or (especially) in the field.

As I mentioned in the initial review, the CTX-10 owner is one who operates casually and values a very simple, straightforward radio. Those who want a sturdy, no-frills, set-it-and-forget-it rig. If that’s you, take a closer look at the CTX-10: it may just suit your needs if you’re not planning on using it on Field Day or during RF-dense contest environments.

If, however, you’re looking for a full-featured QRP radio with many of the features and nuanced adjustments you’d expect in the shack, check out the Yaesu FT-818, Elecraft KX2, Elecraft KX3, lab599 TX-500, or the Icom IC-705. All of these rigs are excellent.

The two major advantages of the CTX-10 over competitors are:

the ability to charge the internal batteries from almost any voltage source, and
a higher TX duty cycle (without needing to add external heat sinks).

I believe the CTX-10 will have appeal for radio enthusiasts who value these characteristics:

All-in-one-box portability with no extra wired accessory components
Best-in-class internal battery life
Best-in-class intelligent battery charging
Digital modes like FT-8 and the ability to operate them in the field from internal batteries for extended periods of time
Very few manual adjustments
Broadcast listening, as the CTX-10 is also a broadcast receiver
Best-in-class hardware

The CTX-10’s overall construction and components are, as I’ve said, near mil-spec. While the CTX-10 isn’t weatherized or waterproof––no more than any of its current competitors (save the TX-500)––the construction is top-shelf, for sure. It should run for decades without need of repair.

Although I can’t recommend to the CTX-10 for serious radio operators, it is built like a tank, and has a simple feature set for field operation. It’s also designed and manufactured right here in the USA. All the better.

Click here to check out the CTX-10 at CommRadio.

Click here to check price and availability at Universal Radio.

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Initial review of the CommRadio CTX-10 QRP general coverage transceiver

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[Update: Please note that we’ve now posted a final review of the CTX-10 which builds upon the review below. Think of of the final review as the second installment, or “Part 2? of this review. If you’re considering the purchase of a CTX-10 please read this initial review first.]

In the past two years few QRP transceivers have generated the interest of the CommRadio CTX-10. I’ve gotten no fewer than two dozen emails from readers asking about the CTX-10 after learning I had one here at SWLing Post HQ. And, I’ll freely admit, I was among those people who couldn’t wait to give this promising little radio some on-air time––and, as a result, a proper evaluation.

The CTX-10 arrives in this simple box.

Everything included in the CTX-10 box.

There are a few reasons why the CTX-10 has stirred up so much excitement. Firstly, the CTX-10 transceiver is based on the excellent and well-regarded CommRadio CR-1/CR-1A receiver. Click here to read our review in a new window.

Fans of the US-made CR-1 and CR-1A appreciated the approach to the CommRadio design: simple operation, clever engineering, near-mil spec components and construction, superb receiver characteristics, as well as excellent audio. The classic CR-1 has all the essentials––multiple modes, filters, and the like––yet offers relatively few features when compared with other tabletop radios in its price class. It’s a simple get-on-the-air rig that feels like it’s engineered to last forever. Indeed, its design approach reminds me of the Lowe receivers of days gone by.

Another reason for the unusual level of interest is that the CTX-10 has been in the works for a long time. It was first announced over two years ago in October, 2016, and only started shipping in July/August 2018.

Since then, there have been very few CTX-10 reviews posted…hence all of the email questions.

In early October 2018 Don Moore, President of CommRadio, sent me a loaner CTX-10 which I’ve been using regularly since, testing all aspects of this little 10-watt transceiver.

Even though I’ve had the radio for a while, I plan to post a final CTX-10 review in the SWLing Post in coming months. As you may know, I typically only keep a review unit two months before publishing an evaluation, so why the delay? In short: I feel like the CTX-10 has some important updates/upgrades that need to come down the line, and I’m allowing time for these to be developed and tested before I issue a full and final review. So, if this is a rig that interests you, you’ll want to stay tuned for that.

In fact, due to a couple of quirks that only affected the first twenty production units, CommRadio has already replaced my initial review unit. I’ll detail these quirks below.

In the meantime, what follows is an initial review of the CommRadio CTX-10 with the most current firmware as of time of posting (1311). This review format is a departure from previous reviews as I’m only focusing on the pros and cons that might help future CTX-10 owners make a purchase decision.

Consider this initial review just a taste of the CommRadio CTX-10, not the full course.

CTX-10: The Pros

First of all, much like the CR-1 and CR-1A, the CTX-10 is an all-in-one unit that takes fewer than five seconds to get on the air if you have an antenna at the ready. Seriously. Other than a key, and/or microphone and antenna, there are no other external attachments needed. It’s field-ready from the moment you remove it from the package.

True story: it took me all of thirty seconds to remove the CTX-10 from the box, plug in a key, an antenna, and have it on the air. This is a major pro, in my radio world.

ATU

The CTX-10 has a built-in automatic antenna tuner that seems to do a great job making 1:1 matches on near-resonant multi-band antennas. I have a large horizontal multi-band delta loop here at the QTH, and the CTX-10 does a fine job finding a match on most ham bands.

Can it match the performance of the Elecraft KX-series ATU? I haven’t done an A/B comparison yet, but I don’t expect so—not on random wire antennas, at least. I do think, however, it will easily match any proper field antenna you pack in your go-kit.

Another minor plus worth mentioning? The ATU is very quiet in operation.

Internal batteries

The CTX-10 ships with three built-in #18650 3.7V 2600 mAh rechargeable Li-ion batteries that are user-replaceable. These are high-capacity cells—in fact, the same type of cells used in the Tesla Model S.

But how do they work? In short: brilliantly. They power the CTX-10 for a much longer period of time than the battery pack in my Elecraft KX2.

After a full charge, these cells will support casual operation for up to eight hours. If you’re using the CTX-10 in a contest or on Field Day where operation is intense––that is to say, near-constant transmitting––it should last the better part of an hour. Don Moore actually produced a video early on of the CTX-10 running a full 10 watts and transmitting dits in CW for forty solid minutes before the batteries depleted to the point of shutting down. That’s certainly a new benchmark for portable rigs with internal batteries.

The CTX-10 has an intelligent charger that will recharge the internal cells when any voltage over 5 VDC is applied. This means, in a pinch, even a typical USB charger will work. If the power supply can deliver up to ten watts, it’ll charge the batteries rapidly––anything below that will take a longer.

Elecraft KX2 (left) and the CommRadio CTX-10 (right)

I also own the Elecraft KX2 and have used it in the field more than any other portable transceiver I’ve owned up to this point.

The KX2’s battery charging routine is more involved than that of the CTX-10. The KX2’s pack must be removed from the radio (by opening the bottom plate of the chassis with two thumb screws, and unplugging the coaxial connector), then it must be hooked up to an external battery charger, charged, and then re-inserted in the KX2.

In contrast, the CTX-10 only requires plugging it into a power source that can provide anything from 5 – 20 VDC––in other words, pretty much any power source. All of the intelligent charging is built into the CTX-10.

Without a doubt, the CTX-10 has the most robust and well-designed internal battery charging system I’ve ever found in a portable radio. Period.

Best-in-class duty cycle

If you’re a fan of FT-8 and other high-duty cycle digital modes, you’ll be very pleased with he CTX-10.

Like many other hams, I was bitten by the FT-8 bug. FT-8 is an amazingly efficient digital mode that somehow manages to defy propagation—even when transmitting at low power. In the past, I’ve worked all time new countries on five watts!

The CTX-10 back panel.

At home, I designated the Elecraft KX3 as my primary FT-8 rig. First time putting it on the air, I found to be fairly effortless. However, after operating perhaps 15-20 minutes, I found that power levels decreased significantly. This is because taxing the finals with FT-8 produces a lot of heat, and the KX3 protects the finals by lowering the output power. KX3 owners wishing to play FT-8 for extended periods at 10 watts or higher know how important it is to purchase an aftermarket heatsink to give the KX3 more transmitting time.

The CTX-10, in contrast, needs no aftermarket additions—if anything, it’s over-engineered. The entire chassis of the radio is essentially a heat sink, and because of this, it requires neither additions nor a fan to cool the finals, leading to comparatively effortless operation. Plus, as a result, operation is completely quiet.

In short? No overheating finals with the CTX-10: it’s an FT-8 beast!

Receiver performance

Overall receiver performance is what I expected: nearly identical to the CommRadio CR-1/CR-1a receiver series with the added benefit of an internal ATU that helps tweak the antenna match on the ham bands.

Simple operation

You can tell that CommRadio has a legacy in designing equipment for the military, as well as for commercial and aviation industries. The CTX-10 smacks of a channelized commercial radio. There are relatively few features and adjustments as compared with, say, the Elecraft KX2 or the LnR LD-11. For those who like basic controls, the CTX-10 should please. On the other hand, if you like more granular control of your transceiver, you might prefer more refinements.

Quality engineering and construction

Like the CR-1A, the CTX-10 enclosure is aluminum with machined aluminum knobs. The boards and internal components are near (if not) mil-spec––brilliant quality that is found in few other radios.

The OLED display is easy to read at any angle and under almost any conditions you might experience at home or in the field––truly best-in-class in this regard. It is a relatively small display, but crisp and high-contrast, so quite easy on the eyes.

The circuit boards inside are of the highest quality, and so are the components. Don Moore sourced them from the same suppliers he uses for commercial-grade equipment.

My good friend, Vlado (N3CZ)––radio engineer and repair technician––took a look inside the CTX-10 chassis; he was sincerely impressed by the quality of the construction and board design. It’s worth noting that Vlado isn’t easily impressed, as he looks at the internals of commercial and military grade communications equipment every day: thus it says something that he remarked on this rig’s quality.

CTX-10: The cons

I’ve covered the obvious positives, so what about the negatives?

What follows are the cons I’ve noted while operating the CTX-10.

Keep in mind, some of these cons may disappear with future CTX-10 firmware updates. Again, I plan to hold off on my full and final CTX-10 review until I feel CommRadio has essentially finished planned upgrades.

At least for now: only one VFO

[Update: A/B VFOs and split operation were added to the CTX-10 via a firmware update in 2019. Please read our final review for details.]

Herein lies my biggest gripe with the CTX-10 and what I would consider a glaring omission on a $1,000 modern SDR transceiver. However, it’s worth noting that CommRadio has committed to address this in an update–see below.

At time of posting, the CTX-10 doesn’t have A/B VFOs like almost all modern transceivers––certainly like all of its direct QRP competitors, like the Elecraft KX2/KX3, LnR LD-11, and Yaesu FT-818/817ND.

So, how does a lack of two VFOs impact operation? First of all, there is no way to operate split on the current version of the CTX-10. Ouch.

The first time I put the CTX-10 on the air it was at the QTH of Vlado (N3CZ). We put the CTX-10 on 40 meters, and one of the first stations we heard was in Vanuatu, due to a brilliant opening into the Pacific. Vlado was positive he would work them with 10 watts on his 40M Steppir Yagi––I was, too. This being the first time either of us attempted DX on the CTX-10, we plugged in Vlado’s Bencher paddles and quickly tried to sort out where the DX station was working his pileup.

It was then we realized that the CTX-10 had no second VFO to work split, and, hence, we couldn’t work the Vanuatu station––because, like pretty much any desirable DX, he was operating split. Frankly, I was in disbelief and quickly downloaded the latest CTX-10 manual to find out how to engage split, but there was no mention of it in the manual.

The only other option was to operate split using a RIT control to shift the receive frequency. Again, we couldn’t locate a RIT control and a search of the manual proved no mention of RIT because, alas, there is no RIT control.

Again, we couldn’t work Vanuatu on the CTX-10 because, like all good DXers, the Vanuatu team were operating split.

Update: CommRadio has informed me they will be adding A/B VFOs as soon as possible, certainly before the 2019 Hamvention in mid-May, but hopefully sooner.

Update 2: Split operation added June 2019. Please read our final review for details.

Features may be too basic for some ham radio operators

It’s no secret: most of us hams like to fiddle with controls to tweak a transceiver’s performance. This is why ham radio transceivers often feature even more controls than their commercial/military counterparts.

The CTX-10 support feet are easy to flip up. The operating angle is excellent.

Still, some operators do appreciate a simpler rig, as they prefer simply to get on the air and get the job done. I appreciate this, too, especially when engaged in field operations where I’m less inclined to tinker with settings. So there’s some appeal in the CTX-10 approach.

At present, the CTX-10 feature set is very basic. Here’s a list of common controls the CTX-10 lacks––many that I’d typically expect in a radio of this price class:

No RF Gain control. The CTX-10’s RF gain is directly tied to the three AGC settings (slow, medium and fast). I know operators who never reach for the RF gain control, but I do, especially in the summer when it’s such an effective tool to lower QRN levels and help DX pop out of the background.

No microphone gain control. The CTX-10 lacks a mic gain control. The microphone input has a limiting pre-amplifier with built-in compressor and ambient noise gate. Problem is, at present, these settings are fixed and cannot be manually adjusted by the user. The CTX-10 was designed to work with handheld mics positioned closely to one’s mouth. Early feedback from users indicated that the CTX-10 was a little too aggressive, cutting off speech; a recent update did address this concern. Some users might never notice the lack of a mic gain control if they stick with the suggested modular MFJ-290MY or Yaesu MH-31A8J handheld mic. Personally, though, I like having a little more control of my microphone performance.

Keep in mind, there’s a plus side to the CommRadio ANG (Ambient Noise Gate): extended battery life. If you have the microphone keyed down, yet aren’t speaking for longer than a second or two, the output will be gated OFF, preventing background ambient noise from being transmitted. The on/off gating happens very quickly and isn’t noticeable.

The CTX-10 currently has no passband (PBT) control, notch filter or noise blanker.

Microphone compression is also pre-configured, and there’s currently no way to manually adjust it. This is a design choice typical of commercial communications gear.

No QSK/full break-in operation. The CTX-10, like the LnR LD-11, uses a traditional relay for switching between transmit and receive. Some CW ops like to hear the received audio between the dits and dahs of their sent CW. Elecraft radios, for example, use PIN diode T-R switching to eliminate relays during QSK. The CTX-10 uses a relay, so during CW operations, you’ll hear the relay click when switching from TX to RX and back again. This isn’t a problem for me, as I rarely set my CW rigs for full break-in, but the CW hang time delay on the CTX-10 is not currently adjustable. For high-speed CW ops that prefer a faster relay recovery, I suspect this could be an annoyance.

Limited CW adjustments. The CTX-10 lacks other controls many of us CW operators appreciate. Currently, the CTX-10 lacks a sidetone control––you cannot change the sidetone volume, nor can you turn it off. I believe CommRadio plans to fix this quirk in a future firmware upgrade. Additionally, you (currently) can’t change which side of your paddle sends dits and dahs without re-wiring your paddle. A minor con, for sure. Still, most modern QRP transceivers allow you to change this from the radio––I imagine CommRadio could add this feature in the future if their customers want it.

In addition, when operating the built-in CW keyer at speeds north of 25 words per minute, both Vlado and I noticed that immediately following a TX-RX-TX relay recovery, CW keyer timing was a little flaky. We assumed there was a problem with our paddles (perhaps dirty contacts?), but that turned out not to be the problem. Difficult to characterize, but essentially: immediately after a TX-RX-TX relay recovery, it’s hard to form a word correctly. The letter “Y” might come out as a “K” or “X” and a “Q” might come out as a “Z.” Both Vlado and I believe this might have something to do with keyer timing, which is possible. Nonetheless, I’m confident this can be fixed with a firmware update. In addition, we worked my friend Mike (K8RAT) and while he had very positive comments about the CW tone in general, he did notice truncated elements following a TX recovery. He also noticed an occasional slight tone spike on the first element which seems to coincide with an audio pop we hear in the sidetone. Note: CommRadio fixed this issue in a 2019 firmware update. Read our final review for details.

Accident-proof ATU activation. As with the CR-1A receiver, most of the CTX-10’s features and options are controlled by accessing the menu system by pressing the volume control knob. To make ATU activation easy, CommRadio place the ATU function first in the menu––with one knob press, the ATU item appears, and with one more press the ATU activates and tries to find a match. Engaging the ATU, in my opinion, is just a little too easy. With two presses of the volume knob, the ATU engages––great, but I find this happening by accident simply by normal handling of the radio. Instead of two short presses to engage ATU, I feel it might be best when making one short then one long press.

One other minor note: the CTX-10 ATU configuration cannot be adjusted manually like it can on the Elecraft KX series ATU.

No keylock to prevent powering up and engaging ATU. The CTX-10 does have a keylock to prevent the encoder from shifting during operation (a great feature for FT-8, for example), but it lacks a keylock to prevent the main power button from being pressed and turning on while in transport. Even more worrisome would be turning on the unit and engaging the ATU while in a pack––I’m guessing this could eventually damage the radio’s finals. The current solution for this? CommRadio suggests tying a shielded wire around the post of the volume control. This prevents accidental pressing while in transport and the CTX-10 ships with one of these around the volume knob (to prevent it turning on in shipment). I feel a more elegant solution would be to design it so that, in order to power up the CTX-10, you’d press two buttons simultaneously: for example, the volume control and the STEP buttons. I’ve make this suggestion to CommRadio. Update: Via a 2019 firmware update, CommRadio added a feature that automatically turns off the radio if accidentally turned on during transport. This is not a keylock and will not prevent the ATU from activating of the power button is accidentally pushed twice, but it will prevent the radio from being powered on in a pack until the batteries have been depleted.

Minor concern: no noise reduction control. In truth, this is a very minor con in my opinion. I’m not a big user of DSP noise reduction, but some users expect it on modern transceivers. I feel like the CTX-10’s receiver is well-balanced so I wouldn’t reach for a noise reduction control under normal operating conditions. That said, since there is no manual RF gain control, a variable noise reduction control could come in handy when QRN is heavy.

Size comparison: My ultra-compact C. Crane CC Skywave SSB sitting on top of the CommRadio CTX-10.

Minor concern: limited power output levels. This is a very minor gripe for me, but again could be important for other ops. At present, the CTX-10 has only three power output levels: 1, 5, and 10 watts. Thus for low-power contests, there is no way to lower the CTX-10 below one watt and no adjustment to zero watts. A couple of years ago my radio club had a DXCC 500 mW challenge to see who could work 100 countries with 500 mW or less. Most other modern QRP transceivers in this class have more nuanced control of power output and can be set to 1/2 watt. At present, the CTX-10 cannot. This is truly a minor complaint––perhaps only important to 10% of CTX-10 owners at best––but I’m willing to bet this could be added via a firmware upgrade.

Early production run quirks now resolved

Fortunately, however, the CTX-10 is listening to their market, and has resolved a number of early production run quirks. My initial evaluation loaner unit was serial number #19. Turns out, some of the first production run units (including mine) had a couple of hardware quirks. CommRadio has replaced or fixed these issues when customers report them, and units currently in inventory aren’t affected. I list them here simply to document:

Resolved: Intelligent charger whine. When charging the internal Li-Ion cells, my evaluation unit produced a high-pitched audible whine. I measured the audio frequency with a simple smartphone app and determined that it hovers around 10.5 kHz. The replacement unit doesn’t have this problem.

Resolved (or repairable): Internal speaker distortion. The internal speaker on some of the early units was prone to vibrate against the bottom plate of the radio’s chassis. This produced a buzzing distortion on loud sounds or when the volume was increased above, say, 50%. Again, this only affected some of the initial production run units. The fix for this is quite easy, and either CommRadio will do this for you or you can do it yourself and get a warranty extension, so if you find this to be a problem with your early unit, contact CommRadio.

Conclusion

To my knowledge, the CTX-10 is CommRadio’s very first ham radio transceiver. But it’s not the company’s first foray into transceiver equipment, as they’ve a solid history in commercial, aviation, and military electronics.

My biggest criticism of the CTX-10 is that I feel it should have never been released without A/B VFOs. Fortunately, this was addressed in a 2019 firmware update. I trust this company, so I know they will follow through; I’ve even offered input on how split operation might be implemented with the A/B VFOs. Personally I wish the rig sported a little more in the way of CW controls, mic gain, and an RF gain control, too––but that’s my preference, controls I like to use. Again, the CTX-10 feature set might be a little too thin––too simplistic––for some hams.

That said, I never expected the CTX-10 to have the number of features that, say, the KX2 has––the CTX-10 isn’t intended to be a “Swiss Army Knife” radio like the KX2/KX3. In fact, CTX-10 development actually began around the same time the KX2 was introduced to the market, and its introduction didn’t deter CommRadio.

CommRadio firmly believes that the CTX-10 will still have appeal to current KX2/KX3 owners and QRPers who value their design philosophy of simplicity. And, what’s more…they have a point.

So, who is the CTX-10 for?

When I check out a new-to-the-market radio like the CTX-10, I always try to sort out who the customer is––what type of ham radio operator would reach for the CTX-10 over other transceivers.

After having spent the past few months with the CTX-10, I can tell you that the CTX-10 owner is one who values a very simple, straightforward radio––one that appears and functions more like a commercial or military channelized set. Perhaps someone who began operating in a commercial, military, or aviation field, and/or who likes the “get on and get the job done” approach. Someone more interested in making contacts than in radio operations and refinements. Those who want a sturdy, lasting, no-frills, set-it-and-forget-it rig. If that’s you, take a closer look at the CTX-10–it may just suit your needs to a T.

The CTX-10’s overall construction and components are, as I’ve said, near mil-spec. The CTX-10 isn’t weatherized or waterproof––no more than any of its competitors––but the construction is top-shelf, for sure. It should run for decades without need of repair.

The whole body of the CTX-10 is essentially a heat sink.

I believe the CTX-10 will have strong appeal for radio enthusiasts who value:

All-in-one-box portability with no extra wired accessory components
Best-in-class internal battery life
Best-in-class intelligent battery charging
HF packs
A high duty cycle and no cooling fan noise or third-party heat-sink add-ons
Digital modes like FT-8 and the ability to operate them in the field from internal batteries
The equivalent of a simple portable military/commercial set
Robust audio from a radio’s internal speaker or headphones
A well-balanced receiver with few manual adjustments
Broadcast listening (the CTX-10 is also superb broadcast receiver)
Best-in-class hardware

The CTX-10 is built like a tank, and has brilliant receiver characteristics. It’s also designed and manufactured here in the USA, and I find it’s easy to get good support from CommRadio.

I will add that CommRadio has been very receptive to my constructive and frank criticism. A good thing, in my book, as lesser companies might take offense or simply be dismissive.

If you’ve been waiting to purchase the CTX-10, I hope I’ve given you enough information that you can make a decision.

If you have any specific questions, please contact CommRadio or comment, and I’ll do my best to answer. I hope to post a few videos of the CTX-10 in action within the next few weeks when my rather busy schedule permits.

Please click here to read our final review of the CommRadio CTX-10.

Click here to view the CommRadio CTX-10 at CommRadio and at Universal Radio.

For a full list of CTX-10 features and specs, I would encourage potential owners to download and read the CTX-10 Operator’s Manual, available on the CommRadio website.

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Winter radio life and preparing for power outages

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Listening to a local station with the BC-348-Q until we lose power.

Here at SWLing Post HQ we’ve been under a Winter Storm Warning since yesterday–it’s not set to expire until sometime tomorrow. This storm hasn’t been all snow–it’s a mixture of snow and ice. If this continues, I fully expect to lose power at some point today.

In general, we’re prepared to handle this sort of thing: our refrigerator and freezer are powered by solar and completely off-grid, we have a super efficient RAIS woodstove to keep us warm and of course, we have a generator at the ready if needed.

Playing radio off-grid

As I write this post, I’m listening to the Signal Corps BC-348-Q (photo above) which is tuned to a local AM broadcaster. It’ll fill my shack with local news/tunes and its vintage valves will do a fine job warming this small room until the power eventually goes out.

When it does go out, I’ll switch to my blackout buddy, the CommRadio CR-1A.

I find that the CR-1A is nearly ideal for off-grid and field listening, as long as you have a good external antenna. The internal Li-Ion battery powers the thing for ages and it has an incredibly capable receiver.

Of course, I also have an Elecraft KX3 and KX2 which can be powered by battery, but I tend to use the CR-1A for broadcast listening and save the KX2/KX3 for off-grid ham radio QRP fun.

In addition, I have the new battery-powered CommRadio CTX-10 transceiver in the shack.

I’ve been receiving numerous emails about this particular field rig because there are so few CTX-10 reviews out there even though it’s been on the market since late July.

Please note that I’ve been giving the CTX-10 a thorough evaluation over the past few weeks and plan to publish my initial review in the next few days.

Bye-bye noise!

Even though I live in a very rural and remote area with little-to-no RFI, when the power is cut, my noise floor still drops . We’re not immune–like most homes, we have power supplies and devices that emit radio interference.

It’s funny: most urban radio enthusiasts I know don’t fear power outages, they prepare for and embrace them! When all of those RFI-spewing devices go silent, it’s simply amazing what you can hear from home on frequencies below 30 MHz with pretty much any receiver.

Personally, as long as I have a means of 1.) powering my radios, and 2.) making coffee (extremely important), I consider myself properly prepared.

I’ve always got those two points covered.

Bring it, old man winter! I’m ready to play radio!

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The CommRadio CTX-10 has landed

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Yesterday, UPS delivered a much-anticipated package: the CTX-10 QRP transceiver from CommRadio.

CommRadio dispatched this loaner CTX-10 for evaluation and I’m excited to get my hands on it since it’s not everyday I get to evaluate a transceiver designed around field portability (my favorite category of gear).

Yesterday, I took a few shots of the CTX-10 as I unpacked it:

I’ll need to build a fused power cable with the supplied pigtail and also sort out an 8 conductor (Yaesu compatible) modular plug microphone. Of course, I’ll give this radio a thorough review testing it on SSB, CW and digital modes (especially FT8).

Since the CTX-10 is built on the CommRadio CR-1 and CR-1A I anticipate a capable receiver section (in other words, expectations are high). Of course, I’ll test the CTX-10’s ability as a broadcast receiver as well.

Follow my progress by following the tag: CTX-10

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CommRadio CTX-10 availability update

CommRadio CTX-10 approved by FCC

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The CommRadio CTX-10

Many thanks to SWLing Post contributor, R. Lewis (KF5GV), who writes:

Just noticed on Universal Radio web page the Comm Radio CTX-10 has been approved by the FCC. They are accepting pre-orders on Dec 1. No indication of pricing but hope they announce it soon.

Thanks for the tip!

I’m looking forward to checking out the CommRadio CTX-10. For one thing, it’s in one of my favorite radio categories: portable general coverage QRP transceivers!

Since the CTX-10 receiver is likely an iteration of the excellent CommRadio CR1 series, I expect it’ll perform well on the broadcast bands as well as the ham bands. I look forward to reviewing the CTX-10.

The new CTX-10 prototype from CommRadio at Universal Radio’s 2017 Hamvention booth.

Follow the tag CommRadio CTX-10 for updates.

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